1. Field of the Invention
This invention in general relates to a fully-automatic system or apparatus for producing a cord length with a plug. More particularly, the present invention is concerned with an improvement in apparatus for producing a cord length with a plug whereby the production of a cord length with a plug can be fully-automatically carried out. For producing a cord length with a plug, there are needed steps of measuring, cutting and stripping a sheathed pair of parallel electric wires (a cord); applying an electric terminal element or blade to the stripped end of each of the wires; forming, by injection molding, a casing for the connecting parts between the stripped ends of the wires and the terminal blades; and inspecting the electric performance of the thus-obtained cord length with a plug. The improvement of the present invention enables the above-mentioned steps to be carried out fully-automatically.
2. Description of the Prior Art
Our investigation shows that there has not heretofore been proposed any prior art automatic apparatus in the United States, Japan or in any other countries that, during one operating cycle thereof, can automatically perform all the operations needed for obtaining a cord length with a plug, from the feeding of a sheathed pair of parallel electric wires to the inspection of the electric performance of the obtained cord length with a plug.
In a technical journal, "Journal of Labor Saving and Automation" at pages 68-72, published November, 1979 (Vol. 10, No. 11: No. 120), by a publishing company, Ohm Inc., Japan, there is disclosed an automatic apparatus which, during one operating cycle thereof, can measure the length of a sheathed pair of parallel electric wires, sever the measured electric wires, strip the insulation from the end of each wire, apply terminal blades to the ends of the wires and form, by injection molding, a casing for the connecting parts of the wires and the terminal blades. From a viewpoint of automation, this apparatus may be referred to as one of the pioneer apparatuses in the field. This apparatus, however, has a disadvantage in that the rotation of a terminal blade secured to each of the paired electric wires from its original horizontal position to its vertical position requires very complicated operations. Such rotation of a terminal blade is necessitated prior to the injection molding of a plug casing. More specifically, in the apparatus, the terminal blade is rotated to its vertical position as follows: When a sheathed pair of parallel electric wires having terminal blades applied thereto is laterally conveyed by means of a conveyor assembly to a predetermined location with respect to a terminal blade-rotating assembly, a gripping means, which is a constituent component of said terminal blade-rotating assembly, is advanced toward the terminal blades from the front direction thereof. This gripping means includes a pair of cylindrical legs each having a deep recess. After the pair of terminal blades have been inserted into the deep recesses of the pair of the cylindrical legs respectively, the pair of the cylindrical legs are rotated 90.degree. inwardly with respect to each other so that each of the terminal blades is adjusted to a vertical position and then the gripping means is moved upward. When the gripping means has been moved upward through a predetermined distance, the gripping means is then advanced laterally, namely in a direction parallel to the conveyor chain until the gripping means reaches a position where the terminal blades are released from the recesses provided in the pair of the cylindrical legs. The terminal blades are released from each of the recesses by means of pushing pins which push the terminal blades to disengage them from the recesses. The terminal blades thus released are placed on the final stage section of said conveyor assembly with a predetermined spacing between them, assuring that each of the terminal blades is in the vertical position. The above-mentioned complicated series of mechanical operations is repeated every time when a cord length with a pair of terminal blades is transferred to be unloaded onto the final stage section of the conveyor assembly, thus rendering this particular stage further complicated. In other words, the terminal blade-rotating assembly includes only one pair of cylindrical legs, each having a deep recess, adapted to pick up the terminal blades secured to the ends of a sheathed pair of electric wires so the aforementioned cycle of motion of the gripping means, including said pair of cylindrical legs, is repeated a predetermined number (for example, six) of times before a predetermined number (six) of sheathed pairs of blade-terminated electric wires are collected onto the final stage section of the conveyor assembly (six pairs of blade-terminated electric wires are treated as a group or unit in the next stage for the injection molding of a plug casing), leading to consumption of much time and lowering of the production efficiency.
Another disadvantage of this prior art apparatus is that the mold of an injection molding machine for forming the plug casing is set back from the conveyor assembly. A predetermined number (six) of cord lengths, each having a pair of terminal blades are transferred to the mold of the injection molding machine after being collected on the final stage section of the conveyor assembly, maintaining each terminal blade in the vertical position. It should be noted here that, in this prior art apparatus, a cord length is laterally conveyed by means of a conveyor assembly from the measuring and cutting machine so that the cord length is first stripped; second, terminated with a pair of terminal blades; and third, picked up, carried and positioned on the final stage section of the conveyor assembly with the terminal blades being arranged in a row with a predetermined spacing between them and adjusted to their vertical position, Next, a predetermined number (six) of cord lengths with terminal blades are transferred to the mold of the injection molding machine by means of an inserting head. At this time, however, the direction of movement of a predetermined number (six) of cord lengths, each having a pair of terminal blades is all of a sudden changed and the cords are transferred in a direction perpendicular to the axis of the conveyor assembly, because the mold of the injection molding machine is disposed behind the conveyor assembly. This may unfavorably give rise to a phenomenon in which a predetermined number (six) of cord lengths having been transferred to the mold of said injection molding machine still have their tail ends located on the final stage section of the conveyor assembly, their tail ends overlapping and intermingling with the cord lengths which are collected on the final stage section, one-by-one, until the number of cord lengths collected thereon becomes six.
It should also be noted that this prior art apparatus does not include inspection equipment for inspecting the electric performance of each of the finally obtained cords with plugs and sorting good products from rejects.
Accordingly, it properly follows that this apparatus does not provide for full automatic production of cords with plugs.
In Japanese Patent Application Publication No. 56-5033 published on Feb. 3, 1981, there is also disclosed an automatic apparatus for producing cord lengths with plugs with includes a device for transferring a set of cord lengths to the mold of the molding machine for forming a plug casing after each of the terminal blades secured to the set of cord lengths is adjusted to a vertical position. Such device is in the form of a rectangular framework cord length carrier. This rectangular framework cord length carrier includes a plurality of cord length clamps, each adapted to releasably grip a terminal blade so that a set of cord lengths can be mounted on the cord length carrier with their terminal blades adjusted to their vertical position and arranged in a row with a predetermined spacing between them. The rectangular framework cord length carrier is moved by means of a conveyor means along an endless guide track so as to convey a set of blade-terminated cord lengths to the stage for injection molding of a plug casing. The cord length carrier also serves as a plug casing-forming auxiliary molding flask when the set of blade-terminated cord lengths carried thereby are subjected to injection molding for forming a plug casing. Illustratively stated, the cycle of motion of the rectangular framework cord length carrier according to this conventional apparatus is as follows: A set of cord lengths, each having a pair of terminal blades, are first placed on the cord length carrier stationed at its starting position so that their terminal blades are arranged in a row with a predetermined spacing between them and are in their vertical position. When a set of blade-terminated cord lengths have been placed on the cord length carrier in the above-mentioned manner, the cord length carrier is moved along the endless guide track until it gets to the mold of the injection molding machine for forming a plug casing. After completion of the molding of a casing for the connecting parts between each of the cord lengths and its terminal blades, the cord length carrier is then moved via a molded casing cooling equipment to a position where each cord length with a plug is taken off the cord length carrier. At this final stage section, means are provided for taking the final products off the cord length carrier at a time. Such means is in the form of a gatherer, including a set of pairs of jaws adapted for gripping. Thereafter, the emptied cord length carrier is further moved along the endless guide track so that the cord length carrier is returned to its starting position and reset for the next cycle of motion. Thus, the prior art automatic apparatus allows a plurality of blade-terminated cord lengths to be transferred at a time to the stage for injection molding of a plug casing and, further, to the final stage section where each of the final products (cord lengths with plugs) is taken off the cord length carrier by means of a gatherer, including a set of pairs of jaws adapted for gripping.
In Japanese Patent Application Publication No. 56-5033, however, there is no specific description of how a set of blade-terminated cord lengths are transferred from the preceding stage section and placed on the cord length carrier stationed at its starting position. It appears that a set of blade-terminated cord lengths are manually transferred and placed on the cord length carrier while rotating their terminal blades to their vertical position and arranging them in a row with a predetermined spacing therebetween.
As described, the cord length carrier includes a set of cord length clamps provided thereon and adapted to releasably grip a set of cord lengths, each having a pair of terminal blades. A set of blade-terminated cord lengths are firmly held on and released from the cord length carrier by opening and closing the set of cord length clamps on the cord length carrier. It should be noted here that the cord length clamps are biased to an open position not automatically, but manually in this prior art apparatus, i.e., an operator presses down a pedal so as to open the cord length clamps. Thus, in this prior art apparatus, there are, in fact, two operations accomplished manually by an operator, i.e., the transferring of a set of blade-terminated cord lengths to the cord length carrier stationed at its starting position and the opening of the cord clamps on the cord length carrier. The opening of the cord length clamps is necessarily conducted prior to said transferring of a set of blade-terminated cord lengths to the cord length carrier and prior to the taking of the final products (cord lengths with plugs) off the cord length carrier at the final stage of the operating cycle of the apparatus. In view of the above, this prior art apparatus will be most properly referred to as a "semi-automatic apparatus" for obtaining a cord length with a plug.
Another disadvantage of this apparatus is that, as is the case with the apparatus described in "Journal of Labor Saving and Automation", the plug casing injection molding machine configuration of the apparatus is such that it is located at the back of the apparatus. More specifically and referring to the cycle of motion of the aforementioned rectangular framework cord length carrier, the cord length carrier, after a set of blade-terminated cord lengths have been placed thereon at its starting position located at one end of the first side of the guide track of a six-sided shape (which would be formed by cutting out the right-hand lower rectangular corner portion from a rectangular shape), is moved along the first side of the guide track to get to the "preliminary position" for the subsequent plug casing injection molding located at the other end of said first side. The direction of movement of the cord length carrier is subsequently changed 90.degree. inwardly and the cord length carrier is moved along the second side extending from the "preliminary position" to get to the mold of the plug casing injection molding machine disposed behind the "preliminary position". With such a plug casing injection molding machine configuration which is similar to that of the apparatus described in "Journal of Labor Saving and Automation", this apparatus also suffers from a disadvantage that a set of blade-terminated cord lengths having been transferred to the mold of the injection molding machine having their tail ends still remaining on the "preliminary position" for the subsequent plug casing injection molding. In order to prevent the tail ends from overlapping and intermingling with the next set of blade-terminated cord lengths, the cord length carrier with the next set of blade-terminated cord lengths placed thereon is retarded in its advancement to the "preliminary position" until the plug casing injection molding operation for the preceding set of blade-terminated cord lengths is finished and their tail ends are completely removed from said "preliminary position," resulting in the entire advancing flow of cord length carriers being slowed up. Such slowed up conveying operation will necessarily lead to a large decrease in production efficiency.
It should also be noted that, as in the case of the apparatus described in "Journal of Labor Saving and Automation", this apparatus does not either include an inspection equipment for inspecting the electric performance of each of the final products. It is concluded from the above that the apparatus described in Japanese Patent Application Publication No. 56-5033 is incapable of automatically performing, during one operating cycle thereof, all the operations needed for obtaining a cord length with a plug, i.e., from the measuring, cutting and stripping of a sheathed pair of parallel electric wires to the inspecting of a finally-obtained product with respect to its electric performance. This apparatus is rather a semi-automatic apparatus for obtaining a cord length with a plug which is capable of automatically performing only part of the operations in the entire cord length with a plug producing process.